REGULATION OF ALDOSTERONE SECRETION AND ADRENAL RENIN IN TGR(MREN2)27

The transgenic hypertensive rat strain, TGR(mREN2)27, serves as a new model to extend the analysis of the intraadrenal renin-angiotensin system (RAS). They exhibit a strong expression of an additional renin gene (Ren-2d) in the adrenal gland. Here we demonstrate, that, in adrenal cells of TGR(mREN2)27, renin is synthetized de-novo and released in a regulated manner. Renin secretion in the adrenal gland of TGR(mREN2)27 is stimulated by cAMP, angiotensin II (ANGII), and calcium. This is contrary to the known regulation of renin in the kidney. The adrenal RAS of TGR(mREN2)27 may play a role in adrenal steroid metabolism. Thus, the secretion of aldosterone is elevated, and this can be partially prevented by captopril in vitro. Moreover, further stimulation of aldosterone release in vitro by ANGII is diminished. These results indicate elevated adrenal ANGII in TGR(mREN2)27, possibly due to local generation.